Oh wow you have Espeon. I don't know what Pokemon I was thinking. Nah Espeon is a great Psychic, the only advantage Sigi has is better def and flying attacks. That's your call.
Although if you do choose one or the other you'll need a ground or rock type. Gigalith, Krookodile or Trapinch --- Mavs Fan:Official GBASB Vice President/Romancer http://i383.photobucket.com/albums/oo273/Photo_Phreak/alkalinesig2.png
Do like me. Have a backup. Scraggy has amazing def and a great movepool that covers most weaknesses (dark, fighting, elemental punches, etc) so I suggest him being your physical sweeper. I cleaned the 7th gym just using Scrafty and ice punch.
Just equip an exp share and grind a bit to catch it up. Krook is a wonderful choice for ground but you can use him in your main party switching him and Sigi out.
Or you can avoid Sigi completely and go pure flying type with Unfeazant or Altaria --- Mavs Fan:Official GBASB Vice President/Romancer http://i383.photobucket.com/albums/oo273/Photo_Phreak/alkalinesig2.png